PURIFICATION OF A HYDROCARBON STREAM WITH Cr{115 {115 {115 {11 IONS IN SOLUTION

ABSTRACT

Polynuclear aromatic hydrocarbons, and other aromatic compounds and organic sulfur and nitrogen compounds are removed as impurities from petroleum streams by extraction with Cr in a solution of acetone, methanol or ethanol wherein the metal ion complexes with the impurities and is withdrawn with the metal salt solution.

United States Patent [151 3,666,660 Bernheimer 1 May 30, 1972 [54]PURIFICATION OF A HYDROCARBON 1.826.142 10/1931 Lachman ..20s 295 STREAMWITH CR IONS IN SOLUTION [72] Inventor: Ralph Bernhelmer, EastBrunswick, NJ.

[73] Assignee: Esso Research and Engineering Company [22] Filed: Apr.30, 1970 [21] Appl. No.: 33,481

[52] US. Cl ..208/243 [51] Int. Cl ..Cl0g 29/06 [58] Field of Search..208/243, 244,246, 226, 232,

[56] References Cited UNITED STATES PATENTS 3,326,798 6/1967 Hess..208/246 FOREIGN PATENTS OR APPLICATIONS Great Britain ..208/295 Canada..208/232 Primary Examiner-Delbert E. Gantz Assistant Examiner-G. J.Crasanakis AtrorneyPearlman and Schlager and C. D. Stores [5 7] ABSTRACT1 Claim. No Drawings PURIFICATION OF A HY DROCARBON STREAM WITH CR IONSIN SOLUTION BACKGROUND OF THE INVENTION This invention relates to theremoval of impurities from petroleum fractions and more particularlyrelates to the removal of polynuclear aromatic hydrocarbons, sulfurcompounds and nitrogen compounds as impurities from hydrocarbons.

The problem of nitrogen and sulfur removal is particularly important inthe petroleum industry. Sulfur occurs, generally, in the form ofmercaptans, sulfides, disulfides, thiophenes, benzothiophene, anddibenzothiophene. Nitrogen compounds are usually present as heteroatomicorganic compounds, such as pyridines, pyrroles, quinolines, pyrindines,cyclopentaquinolines, indoles, carbazoles, pyrrologuinones, etc.

These nitrogen and sulfur compounds adversely affect many of theimportant refining processes. They are believed to reduce the activityof cracking or hydrocracking catalysts because of their polarity andbasicity. They are also suspected of being involved in gum formation,color formaiton, odor and poor storage properties of fuels.

The polynuclear aromatics, besides being carcinogenic, appear to becolor precursors and hence their presence also has bearing on color andcolor stability problems of lubricating oils.

SUMMARY OF THE INVENTION In accordance with the present invention theabove difiiculties can be overcome by extracting the polynucleararomatic hydrocarbons as well as other aromatic compounds, organicsulfur and organic nitrogen compounds from various hydrocarbon streamsby means of solutions of metal ions. The petroleum fractions containingthe impurities are contacted with the salt solutions whereby metalcomplexes form which can be removed with the solvent phase. Many metalsand many solutions are effective but the transition metals, Fe Cu, andCr as well as Li are most effective. The most effective solvents areethanol and acetone.

Such extraction systems are advantageous because of the low cost of theraw materials, because the solvent and metal salt are recoverable andthe use of a simple counter-current extraction unit employing recyclewill drive the system to completion.

PREFERRED EMBODIMENTS Feed streams suitable for use in this inventioninclude any type of petroleum stream, e.g. light fractions such asnaphthas, lubricating oil fractions, and heavy fractions such aspetroleum residua and tars, in short, any hydrocarbon stream containingpolynuclear aromatic hydrocarbons, and/or nitrogen and sulfur compounds.

The invention is particularly directed to the removal of impurities,particularly nitrogen and sulfur impurities from the above streams bythe use of solutions of metal salts. Suitable metal salts include thoseof Groups 18, IIB, VIB, and VIII of the Periodic System (E. H. Sargentand Company, 1952) and lithium, e.g. Cr(NO FeCl nickelous acetate,nickelic acetate, Ca( N AgNO HgNO and LiBr.

Suitable solvents include any oxygenated and/or nitrogen based solvents,i.e. any highly polar solvent, e.g. water, acetic acid, acetone, ethylalcohol, methyl alcohol, tetrahydrofuran, furan, and peracetic acid.Water may be mixed with the solvent in proportions of from 100 partssolvent to 1 of water to 1 part solvent to 3 of water.

The preferred metal ions are Fe Cu, Cr**"', and Li The preferredsolvents are methanol, ethanol, and acetone.

The solvent to hydrocarbon feed ratio may vary from 1:100 through 1:! to:1.

The process is independent of pressure and therefore is best carried outat atmospheric pressure unless some specific reason dictates higherpressures. The temperature chosen will also, in general, be roomtemperature, although higher temperatures may be used. In general,complex formation of polynuclear aromatic hydrocarbons with the saltswill be promoted by room temperature and slightly above. Complexformation of sulfur and nitrogen compounds may in some instances befavored by higher temperatures.

The following examples are presented as specific embodiments of theinvention but without any intention of limiting the invention thereto.

EXAMPLE 1 To an aromatic sievate obtained by passing a light petroleumfraction through a 5 Angstrom molecular sieve was added 1.0 ppm3,4-benzpyrene (C labeled). Separate lOO ml samples of this mixture wereextracted with various salt solutions and the amounts of benzpyrenedetermined by C counting. The following results were obtained:

% 3,4 Benzpyrene Removed Salt Solvent 24 48 72 96 I66 I-Ir. Hr. Hr. Hr.Hr.

Cr( N0 H O l 0 FeCl CH;,COCH 25 28 24 Cr( N0 Cl l COCl-l 60 Ni(OAc); CHCH OH l8 LiBr CH COCH 38 35 LiBr Tetrahydrofuran 6| 9 Ni( OAc CH COCI-I;3 6 AgNO Furan 25 8.3

(water added) AgNO, Acetone 42 l 1 Cu( N0 CH COCH 72 64 Cr( N0 CH COCH58 Cu(NO CH CO OH l 7 FeCl CH;,CH OH 15 Ni( OAc) CH= CH OH l 8 Ni(OAc)(Cl-l: );CO 3 6 LiBr CH CI-l Ol-I 8 HgNO CH OI-I l4 19 26 FeCl CH Ol-l 7FeCl Acetone 35 34 FeCl Cl-l OI-l 5 Co( OAc) CH Ol-l 6 7 Co( OAc)Acetone 38 37 Cu( N0 Acetone 65 72 (green) Cu( N0 Acetone 52 63 73(blue) .Cr( NQ, Acetone 53 58 62 '0Ac= acetate.

The above data show that all the metals listed and all the solventsexcept water are operable but that Fe Cu, Cr and Li are most effectivewhen used with ethanol and acetone solvents.

EXAMPLE 2 Two percent solutions of each of the four compounds: (A)1,2-diphenylethane; (B) dibutylmaleate; (C) dimethyl pyridine; and (D)benzophenone were added to the sievate used in Example l. Twenty-fiveml. of each of these solutions were mixed with 25 ml. of various saltsolutions and placed in 2 oz. bottles, sealed and shaken for about 12-14hours on a mechanical shaker for an elapsed time of 48 hours. Five ml.samples were removed by pipette and separated into raflinate and saltphase layers in calibrated graduated flasks. The efficiency of theextraction was calculated by U.V. analysis. The following results wereobtained:

l ,Z-DIPHENYLETI-IANE Salt Solvent %Compound Removed Cu( NO, Acetone 4.3Cu( N0, Ethanol 19.1 Cu(NQQ, Methanol 8.6 Cu( N: )1 H 0 1 2.8 V Cr( NO,Acetone 0.0 Cr( N0 Ethanol 23.0 LiBr Acetone 0.0 LiBr Ethanol l 6.8FeCl, Acetone 19. l FeCl, Methanol 8. l l-eCl; Ethanol 26.2

DIBUTYLMALEATE Salt Solvent %Compound Removed Cu( NO Acetone 27.0 Cu(NO,Ethanol 7 l .7 Cu(NOg; Methanol 42.0 Cu( NO, H 0 4.8 Cr( NO, Acetone25.0 Cr( NO, Ethanol 64.3 LiBr. Acetone 20.8 LiBr Ethanol 84.5 FeCl,Acetone 68.8 FeCl, Ethanol 80.9

DIMETHYL PYRIDINE Salt Solvent %Compound Removed Cu( NO, Acetone 96.9Cu( N0 Ethanol 99.9 Cu( N0 Methanol 99.9 Cu(NO 11,0 98.5 Cr( NO Acetone95.4 Cr(NOfl Ethanol 99+ LiBr Acetone S 6.4 Li Br Ethanol 87.6 FeClAcetone 98.9 FeCl Ethanol 99. 3

BENZOPHENONE Salt Solvent %Compound Removed Cu( N0 Acetone 67.0 Cu( N0Ethanol 7 l .2 Cu( N0 Methanol 58.0 Cr( N0 Acetone 75.1 Cr( NO, Ethanol67.7 LiBr Acetone 73.9 LiBr Ethanol 83.8

Fe-Cl FeCl Acetone Ethanol EXAMPLE 3 Hydrocarbon solutions of thiopheneand dibutyl sulfide were extracted, with various salt solutions and thepercent sulfur removed was determined by the Dohrmann microcoulometer.The following results were obtained:

Compound Salt Solvent Removed Thiophene in Octane Nal Acetone 3 3 .7Thiophene in Benzene Cu( N0 )2 Methanol 23 8 Thiophene in Benzene Cu(NO; Ethanol 23.8 Thiophene in Rafi'inate( l) Cu(NO Acetone 43 .7Thiophene in Rafi'inate( l Cu( N09 Acetone 45 .6 Thiophene in BenzeneLiBr Acetone 19.0 Thiophene in Benzene Li Br Acetone 24.4 Thiophene inBenzene Cu( N0 Acetone 52. l Thiophene in Benzene LiBr Acetone 55.3Dibutyl Sulfide in Benzene Cu( N0 Acetone 36.4 Dibutyl Sulfide inSievate Cu(NOQ; Acetone 52.0 Dibutyl Sulfide in Sievate Cr( N0 Ethanol26.0 Thiophene in Sievate Cr( N09 Ethanol 42.0

The sievate ofExample l.

The above data show that sulfur compounds can be satisfactorily removedfrom hydrocarbon solutions.

The nature and advantages of the present invention having thus beenfully set forth and specific examples of the same given what is claimedas new, useful and unobvious and desired to be secured by Letters Patentis:

1. A process for removing polynuclear aromatic hydrocarbons, organicsulfur compounds or organic nitrogen compounds from any hydrocarbonstream, which comprises contacting said stream with Cr" ions in asolution of acetone, methanol or ethanol.

